Lubricating greases from oxo glycols



United States Patent LUBRICATING GREASES FROM oxo GLYCOLS No Drawing.Application October 20, 1952, Serial No. 315,843

12 Claims. (Cl. 252-42) The present invention relates to new lubricatinggreases. More specifically, the invention pertains to new and. improvedlubricating greases having excellent lubrieating properties over a widetemperature range, particularly at extremely low temperatures, and tomethods for making such greases.

In brief compass, the invention provides for the manufacture oflubricating greases on the basis of certain glycols. These glycols arethe oxonation products of cyclic diolefins, particularly non-conjugatedcyclic diolefins, such as butadiene dimers. They are used as such or inthe form of their esters with certain dibasic acids as a lubricating oilbase for the greases of the present invention.

Prior to the present invention, low temperature greases have beenprepared by compounding low boiling mineral oil fractions having lowviscosities with metal soaps in grease-making proportions. However, suchgreases are frequently subjected to relatively high temperatures innormal use. The mineral oil used in making the grease should, therefore,combine low viscosity with low volatility in order to provide efiicientlow temperature lubrication and at the same time prevent oil losses atrelatively high temperatures. Since most low boiling mineral oils ofsufiiciently low viscosity have high volatilitie's, the number ofmineral oils suitable for the production of low temperature greases isvery limited.

More recently, it has been suggested to use certain synthetic oils,particularly certain esters of dibasic aliphatic acids as an oilconstituent for low temperature greases. While greases containing theseesters have highly desirable lubricating qualities as well as excellenthigh and low temperature characteristics, many of these esters areeasily hydrolyzed. The soap and the grease, therefore, must be made inseparate stages. In addition, the available raw materials are ratherlimited. In view of the rapidly increasing demand for greases havingutility over a wide range of temperatures, a broadening of the rawmaterial basis is highly desirable.

It has now been found that certain glycols and some of their esters maybe substituted for low boiling mineral oil fractions and synthetic oilsof the type described above in the production of low temperaturegreases. In accordance with the preferred embodiment of the invention,the glycols used have substituted alicyclic hydrocarbon radicals with atleast two non-conjugated olefinic linkages, one of. which is in a ring,and containing 5-30, and preferably 10-20 carbon atoms. These glycolshave excellent lubricating qualities and combine relatively high boilingpoints with desirably low pour points, high flash points, lowviscosity-temperature coefficients and high chemical stability.

The preferred glycols of the invention may be obtained by subjectingcyclic diolefins, particularly non conjugated cyclic diolefins tooxonation i. e. to a reaction with CO and H2 in the presence ofcarbonylation catalysts, followed by hydrogenation of the product soobtained. In particular, cyclic compounds having one olefinic linkage inthe ring and one olefinic linkage either in a side chain or in anotherring, are adaptable to the process. Thus, it has been found, forexample, that l-vinyl cyclohexene-3 or l-vinyl cyclohexene-4 reacts inthe presence of a solvent, with carbon monoxide and hydrogen to give aproduct which, by hydrogenation, is converted into high yields of glycolcontaining 10 carbon atoms suitable as such or in the form of certain ofits esters, as a lubricating oil constituent of the greases of thepresent invention. This reaction is accompanied to a certain extent byformation of nonyl alcohols, but is substantially unaccompanied bypolymerization and resinification by-products hitherto reported asaccompanying and as being the main product in the oxonation ofdiolefins. Similarly, dicyclopentadiene may be converted by theoxonation or 0x0 process in good yields into a glycol suitable for thepurposes of the present invention, with the simultaneous formation ofCii-alcohols.

This process involves the catalytic reaction of the diolefins dissolvedin a hydrocarbon solvent, such as hexane or heptane, with carbonmonoxide and hydrogen at elevated temperatures of about 225 -400 F. andpressures of about 2000-4000 p. s. i. g., particularly in the presenceof cobalt catalysts, to form aldehydes having 2 carbonyl groups added tothe diolefin originally used. The aldehyde is catalytically hydrogenatedto the corresponding glycol. Minor proportions of lower boilingmonohydric alcohols are formed as by-products. The total hydrogenationproduct is subjected to distillation to remove the monohydric alcoholsand to recover the glycol as overhead product. The distillation residue,i. e., the so-called Oxo-bottorns, is rich in by-product alcohols ofhigher molecular weight.

While the exactcomposition of all these glycols and alcohols is notknown, it is well established that they are mixtures of primaryalcohols. At least a substantial proportion of the monohydric alcoholsis of the branchedchain type. The overhead glycol product consists of amixture of glycols averaging 2 carbon atoms more than the olefinoriginally fed to the Oxo synthesis. It has been found that theseglycols, particularly those containing at least 5, and preferably 10-20,carbon atoms have greatest utility for manufacturing greases inaccordance with the present invention.

For example, the oxonation product of butadiene-l,4 dimer has thecomposition and properties listed below which give it excellent utilityas a grease base.

Composition: Percent C 70.1 H 11.9 0 18.0 Properties:

Boiling Range, C.:

at 3.1-3.3 mm. Hg 153.5-l56.9 at 760 mm. Hg 305-317 Density, g./cc. at25 C. 1.0 Refractive Index N 1.4890

The product also has a desirably high flash point and low pour point aswell as satisfactory viscosity characteristics.

Oxo-glycols of this type and the process of producing the same aredescribed in greater detail and claimed in the copending Staib andStewart application, Serial No. 236,234, filed July 11, 1951, now U. S.Patent No. 2,738,- 370, and assigned to the assignee of the presentapplication. Said copending application is here referred to for specificdetails of the process of producing the x0- glycols.

As indicated above, certain esters may be derived from these Oxo-glycolswhich have likewise excellent lubricating oil characteristics whichrender the same suitable for the preparation of greases in accordancewith the invention. These esters include the products obtained byesterifying C-C3u Oxo-glycols with 2 mols of a mono-basic fatty acidhaving 2-10 carbon atoms per molecule, such as acetic acid, propionicacid, the butyric acids, various C5 acids, caproic acid, etc. Quitegenerally, it may be stated that acids suitable for the production of0x0- glycol esters having desirable lubricating oil characteristics andparticularly flash points of at least 350 F. are preferred.

Lubricating greases in accordance with the invention may be prepared byincorporating into these glycols or glycol esters grease-makingproportions, say about 540 wt. percent, of suitable metal soaps,preferably alkali metal soaps, such as a sodium or lithium soap oralkaline earth metal soaps particularly calcium soaps of high molecularweight, preferably saturated fatty acids having -30 carbon atoms permolecule, such as stearic acid, hydrogenated fish oil acids, etc., or ofa soap-salt complex consisting of the soaps of higher molecular weightfatty acids and the salts of low molecular weight carboxylic acids, suchas acetic, furoic, acrylic or similar acids. The metal soap or soap-saltcomplex is preferably added as such by slurrying the preformed dry soapor complex into the glycol base oil and heating the mixture to 300500 F.while stirring until a homogenous mass is obtained which is cooled toform the finished grease.

When Oxo-glycol esters are used, the grease thickening soap or soap-saltcomplex may be formed in situ. For this purpose, suitable fatty acidsmay be mixed with the glycol ester in grease-making proportions andheated to about 100-200 F. A metal hydroxide, preferably caustic alkali,is then added in aqueous solution and in amounts at least sufiicient toneutralize the acids. The mixture is heated to about 300-400 F. untilneutralization is completed and the mixture is completely dehydrated.Upon cooling, the grease is finished. For the production of lowtemperature greases lithium soaps or lithium soap-salt complexes arepreferred.

The greases may be further modified by the addition of other lubricatingoils, particularly synthetic oils, such as the more readily hydrolyzableesters of dibasic acids, complex esters and others. Other conventionalmodifying agents may be added to the greases of the invention in amanner known to the art. These include thickeners, such asN-stearyl-p-amino phenol, anti-oxidants, such as phenylalpha-naphthylamine and phenothiazine, corrosion inhibitors, such aszinc naphthenate or petroleum sulfonate soaps, tackiness agents, such aspolybutenes, poly acrylate and poly methacrylate esters, load-carryingcompounds, such as sulfochlorinated hydrocarbons or lead oleate ornaphthenate, viscosity index improvers, such as polybutenes or polyacrylate esters, etc.

The preferred thickeners for low temperature greases in accordance withthe present invention are lithium soaps of hydrogenated fish oil acidsor complexes of such soaps with lithium salts of low molecular weightcarboxylic acids of the type described above. It may also be desirableto add small amounts, say, about 0.5-5 wt. percent of a stabilizer tothese greases to improve their texture and consistency. The oxides,carbonates, or soaps of metals forming amphoteric oxides, such as thesoaps of zinc, tin and aluminum, are useful for this purpose.

The invention will be further illustrated by the following specificexamples.

EXAMPLE I A Cm-Oxo-glycol was produced by oxonation of butadiene-l,4dimer as described above. The glycol product is believed to be a mixtureof isomers having the standard formulae given below.

where is the hexahydrobenzene ring. This glycol mixture was heated witha dry complex soap to 500 F. while stirring. The product set up to asmooth uniform soft grease upon cooling.

Wt. Percent Ingredients:

Complex soap, Li-hydroiolate Li-acetate, Mole rat 1 5 Hydrocarbonsolubil Insoluble. Water solubility Not 5 -ln)lc in colrl or hot water.

Hydrofol acids are hydrogenated fish oil acids having a degree ofsaturation corresponding to stearic acid.

This lubricant did not attack rubber.

EXAMPLE 11 The Cm-Oxo-glycol of Example i was esterified with 2 mols ofcaproic acid by heating the mixture of the reactants in the presence ofxylene as a diluent and small amounts of sodium bisulfate as thecatalyst to 305 62 F. for 10 hours. After stripping to a stilltemperature of 392 F. at a vacuum of 4 mm. Hg the weight of the residuewas 250 g.

For purposes of comparison, glycol-centered complex esters of the sameCm-Oxo-glycol with 2 mols of adlpic acid and 2 mols of Cs-Oxo-alcohol,on the one hand, and 2 mols of adipic acid and 2 mols of Cs-Oxo-alcohol,on the other hand, were prepared in a similar manner. The Ca-Oxo-alcoholwas prepared by oxonation of C1 monoolefin polymers in the conventionalmanner. The C9- Oxo-alcohol was the byproduct alcohol obtained in theproduction of the Cm-Oxo-glycol used.

The composition and properties of these esters are listed below in TableI. The esters were all made by heating the charge listed below underComposition with g. of xylene as water entrainer.

Table I A B C 172 g. C:G' 1Y(50l 172 g. Clo-Glycol. 172 g. (ho-Glycol.292 g. Adlpio Ac1d 292 g. Adipic Acid 232 g. Oaproic Acid. I 260 g. Os0x0 Alcohol. 288 g. Co 0x0 Alcohol 100 g. Xylene. Composition(by-product from 010 glycol Manufacur g. llgllafisglrn ou 3.62 g.NlaHS04 2.0 g. NaHSOr. tigg SE? g. eno 1az1ne 3.62 g. P enothrazme. 2.0g. Phenothiazmc.

or eating to 392 F. Still 389.2 533 2 Temperature Under 4 mm. 50 Hg.Vac., g. Prorartietsz O s. a 100 F 66.00 106.20-. US. at 210 F 10.31-12. 05. at 40 F 60,1760 Sol 4,190. Flash, F. 43% 475 395. Pour Point, F65 -35 70.

The above data show a superiority of the caproic acid ester over thecomplex ester with respect to low temperature viscosity characteristics.

Ester C prepared as described was converted into a grease by mixing itwith a dry complex soap and heating the mixture to a maximum temperatureof 510 F. over a period of 3 hours. The molten grease was cooled to 450F. and poured into pans for further cooling. The cold cakes may bereturned to the kettle and worked to a smooth uniform product, filteredand packaged. Cooling may also be finished in the grease kettle whilestirring. The composition and properties of the grease were as follows:

The invention is not limited to the specific figures of the foregoingexamples. The relative proportions of the materials used may be variedwithin the limits indicated in the specification to obtain products ofvarying characteristics.

What is claimed is:

1. The process of making lubricating greases which comprisescatalytically oxonating a cyclic butadiene dimer with Hz and CO atelevated temperatures and pressures conducive to the formation of analdehyde having two carbonyl groups added to said dimer, catalyticallyhydrogenating said aldehyde to form the corresponding mono-glycol,compounding said glycol with grease-making proportions of a soap-basegrease thickener at temperatures of about 300-500 F. while stirring andcooling the grease so formed.

2. The process of claim 1 in which said glycol is esterified with twomols of a monobasic acid having 2-10 carbon atoms per molecule and theester so formed is compounded with said thickener.

3. The process of claim 2 in which said thickener is formed in saidester by neutralizing soap-forming acids with a metal base in said esterat temperatures of about 300-400 F.

4. The process of claim 1 in which said thickener is formed prior tosaid compounding.

5. A lubricating grease comprising a minor greasemaking proportion of agrease thickener selected from the group consisting of the alkali metaland alkaline earth metal soaps of carboxylic acids having from 10 to 30carbon atoms and complexes of said soaps with salts of said metals withlower molecular Weight carboxylic acids and a major grease-makingproportion of a lubricating oil selected from the group consisting ofmonoglycols having 5 to 30 carbon atoms per molecule obtained by thecatalytic oxonation of an alicyclic compound having two non-conjugatedolefinic linkages, one of which linkages is in a ring, with carbonmonoxide and hydrogen at temperatures of about 225 to 400 F. andpressures of about 2,000 to 4,000 p. s. i. g. followed by catalytichydrogenation of the oxonation product; and diesters of said monoglycolswith monobasic carboxylic acids having 2 to 10 carbon atoms permolecule.

6. A grease according to claim 5 in which said alicyclic compound is acyclic butadiene dimer.

7. A grease according to claim 5 in which said alicyclic compound isdicyclopentadiene.

8. A grease according to claim 5 in which said alicyclic compound is1-vinyl cyclohexene-3.

9. A grease according to claim 5 in which said alicyclic compound isl-vinyl cyclohexene-4.

10. A lubricating grease according to claim 5 in which said diestershave a flash point not lower than 350 F.

11. The lubricating grease according to claim 5 in which said monobasiccarboxylic acid is caproic acid.

12. A lubricating grease according to claim 5 in Which said thickener isa soap-salt complex consisting of lithium soaps of hydrogenated fish oilacids and lithium acetate in a mol ratio of 1:1.

References Cited in the file of this patent UNITED STATES PATENTS1,982,198 Brunstrum et al. Nov. 27, 1934 2,575,195 Smith Nov. 13, 19512,575,196 Smith Nov. 13, 1951 2,576,032 Morway et al. Nov. 20, 19512,589,973 Smith et al. Mar. 18, 1952 2,612,473 Morway et al. Sept. 30,1952 2,628,974 Sanderson Feb. 17, 1953 2,639,266 Dilworth et a1 May 19,1953 2,652,361 Woods et al. Sept. 15, 1953 OTHER REFERENCES Wender andOrchin: Critical Review of Chem. of 0x0- Synthesis, Bur. of Mines R. I.4270, pp. 6 and 9, June 1948.

5. A LUBRICATING GREASE COMPRISING A MINOR GREASEMAKING PROPORTION OF AGREASE THICKENER SELECTED FROM THE GROUP CONSISITN OF THE ALKALI METALAND ALKALINE EARTH METAL SOAPS OF CARBOXYLIC ACIDS HAVING FROM 10 TO 30CARBON ATOMS AND COMPLEXES OF SAID SOAPS WITH SALTS OF SAID METALS WITHLOWER MOLECULAR WEIGHT CARBOXYLIC ACIDS AND A MAJOR GREASE-MAKINGPROPORTION OF A LUBRICATIONG OIL SELECTED FROM THE GROUP CONSISTING OFMONOGLUCOLS HAVING 5 TO 30 CARBON ATOMS PER MOLECULE OBTAINED BY THECATALYTIC OXONATION OF AN ALICYCLIC COMPOUND HAVING TWO NON-CONJUGATEDOLEFINIC LINKAGES, ONE OF WHICH LINKAGES IS IN A RING, WITH CARBONMONOXIDE AND HYDROGEN AT TEMPERATURES OF ABOUT 225* TO 400* F. ANDPRESSURES OF ABOUT 2,000 TO 4,000 P. S. I. G. FOLLOWED BY CATALYTICHYDROGENATION OF THE OXONATION PRODUCT; AND DIESTERS OF SAID MONOGLYCOLSWITH MONOBASIC CARBOXYLIC ACIDS HAVING 2 TO 10 CARBON ATOMS PERMOLECULES.